so normal geyser is 138 hours per month at R0.86 p/ kwh is R1.72 per hour R7.91 per day R240.00 per month and R2888.20 per year
solar hybrid geyser 12 hours per month R0.68 per day R20.93 per month and R251.00 per year
so a saving of R2637 per year so +- 9 years to paid back. This is normally less because if you go solar geyser you would be energy effiecient with lights appliances etc etc.
My bill came down from about R1500 to R600 with all we have done which gives me a R10 800 saving a year

Interesting. So what is the sequence? Does cold water first go to the solar heater, from there through the heat pump and finally into the geyser, a in-series installation, or does cold water feed into both the solar panel and the heat pump and then into a common storage tank (geyser?)

The cold water feeds into the geyser (this is where the inefficiency is!) with both the solar heater and heat pump configured as pump arounds from the geyser depending on the reservoir temperature and time of day.

During winter when the incoming cold water is at the lowest temperature, it drops the reservoir temperature instead of first begin pre-heated.

I installed the system when the Eskom rebate system was still active. I can't recall the installation cost...will have to look in the archives!

The heat pump has a 1.3 kW compressor with equivalent water heating capacity of 4 kW. Most summer days the water temperature peaks around 65 deg C on average from the solar system. The heat pump only supports when the solar contribution is poor or during high warm water consumption and the reservoir is depleted during night time. During summer my electricity consumption on the heat pump circuit is on average 60 units. IN winter it is more due to the reduced sunlight period and colder water entering the system. I estimate about 100 - 130 units in winter.

Before I installed the system my geyser circuit averaged 250 units per month in summer time.

Well that's if the system has enough solar and battery to absorb the additional load of charging a car (probably out of solar production time)

Don't necessarily need battery storage to charge an electric car.
Assuming you drive every day in the week, the weekend will charge the car enough for another week /month.

Panels are the cheapest part of a solar system, never hurts to have more than you need (you size systems for winter use, not summer output).

Heck, in summer time, system will start charging before work hours anyway. I start getting solar output on my system in summer around 5:45am onwards. Assuming you leave for work at 7:30am, thats a potential few KW top up every morning.
Eg in my 4KW system, I can usually generate 1-2KW by 6-7am.

I'm building a new house in Steyn City. It will be about 550sqm. I'm looking to go off grid because I actually cannot stand to pay Eskom one cent. I realise it won't be a good ROI but I don't want to be completely roshamboed just because of my hatred of Eskom.

I've just started exploring this option but it's quite overwhelming as I don't know anything about electricity. But here goes:

What solution would someone recommend for going off grid?

I know that I will have to change the way we use electricity. So wash clothes and use dishwasher during sunny days. Try use as much power during the day and only run TVs, lights at night. Not use energy intensive appliances at the same time.

Family of four but may increase to 7 on weekends with relatives staying over

I'm looking to go for two 200l solar geysers on each side of the house with two water rings.

For a start get an estimate of your power consumption, 6×116= 696W for lights only, you can do better and reduce say may be half of that to 3W per light. Get the wattage rating from every appliance you have and add that to get a total power consumption.

A pure sine wave inverter ( I would go with multiple inverters were I in your shoes not just one massive inverter) maybe one for your electronics and another for you heavier appliances like washing machines.It would probably be more expensive but it makes sense to me, since yours is not a backup but a primary power source. Your inverter capacity will be determined by the power consumption of your appliances, e.g. if your total power is 5000W you will need an inverter rated at more than that.

Batteries- Deep cycle, lead acid- cheaper, AGM and lithium- more expensive , higher quality and tech. The number will be determined by the total current your appliances draws, the higher this is, the more batteries you need, the better the quality and their capacity, the longer will be your runtime. Measured in Ah, the higher the AH, the better.

Solar panels to charge your batteries.

You will need an expert to put all of this into perspective, but since you are busy doing your homework you will know which questions to ask. Getting a solar system for a backup is one thing, it being your primary power source is another.

Last edited by thechamp; 21-10-2017 at 07:58 PM.

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